R help - May 2010 - plot for linear discriminant

Hello,

I have a labelled dataset with three classes. I have computed manually the LDA
hyperplane that separate the classes from each other i.e.

\hat{\delta}_j(x)=x^Tb_j + c_j where b_j \in \mathbb{R}^p and c_j \in \mathbb{R}

my concrete b_j looks like e.g. 
b_j <- rbind(1,2)
c_j <- 3

How can I plot y=x^Tb_j + c_j ??  two problems:

1- I need lines and the dimension of my x is 2
2- I would like the plotted lines to end when they intersect so they nicely show
the decision boundaries

Any pointers? maybe an example with ggplot2 I could not find any from the
showcase documentation page ...

Thanks in advance,
Best regards,
Giovanni

Hi Giovanni,

Have a look at the classifly package for an alternative approach that
works for all classification algorithms.  If you provided a small
reproducible example, I could step through it for you.

Hadley

On Sat, May 15, 2010 at 6:19 AM, Giovanni Azua <bravegag at gmail.com>
wrote:
> Hello,
>
> I have a labelled dataset with three classes. I have computed manually the
LDA hyperplane that separate the classes from each other i.e.
>
> \hat{\delta}_j(x)=x^Tb_j + c_j where b_j \in \mathbb{R}^p and c_j \in
\mathbb{R}
>
> my concrete b_j looks like e.g.
> b_j <- rbind(1,2)
> c_j <- 3
>
> How can I plot y=x^Tb_j + c_j ?? ?two problems:
>
> 1- I need lines and the dimension of my x is 2
> 2- I would like the plotted lines to end when they intersect so they nicely
show the decision boundaries
>
> Any pointers? maybe an example with ggplot2 I could not find any from the
showcase documentation page ...
>
> Thanks in advance,
> Best regards,
> Giovanni
> ______________________________________________
> R-help at r-project.org mailing list
> https://stat.ethz.ch/mailman/listinfo/r-help
> PLEASE do read the posting guide
http://www.R-project.org/posting-guide.html
> and provide commented, minimal, self-contained, reproducible code.
>


-- 
Assistant Professor / Dobelman Family Junior Chair
Department of Statistics / Rice University
http://had.co.nz/